Process for using shock waves to produce acetylene



Nov. 1, 1960 P. H. LAHR ETAL 2,953,716

PROCESS, FOR USING suocx WAVES TO PRODUCE ACETYLENE Filed Nov. 20, 1957 2 Sheets-Sheet 1 Defonaring Mixture I N VEN TORS HEADLEE LAMPREY By pflmm A TTORNEY Nov. 1, 1960 P. H. LAHR ETAL 2,953,716

PROCESS FOR USING SHOCK WAVES r0 PRODUCE ACETYLENE Filed Nov. 20, 1957 2 Sheets-Sheet 2 Y INVENTORS I ,PAUL H. LAHR HEADLEE LAMPREY A 7' TORNE Y PROCESS FOR USING SHOCK WAVES T PRODUCE ACETYLENE Paul H. Lahr, Amherst, and Headlee Lamprey, Lewiston,

N.Y., assignors to Union Carbide Corporation, a corporation of New York Filed Nov. 20, 1957, Ser. No. 697,727.

16 Claims. (Cl. 260-679) This invention relates to a novel process for producing acetylene from hydrocarbons by the use of shock waves.

This application is a continuation-in-part of US. ap-

plication No. 538,425 by the same applicants filed October 4, 1955 and now abandoned.

It is known that hydrocarbons, including methane as well as higher aliphatic and aromatic hydrocarbons, will yield acetylene when subjected to partial'combustion or p In thermal cracking proctemperatures and thereby permit recovery of the acetylene itself.

It has now been found that the reaction conditions required for making acetylene from hydrocarbons can be I a detonation. By the term detonation is meant a very rapid combustion in which the flame front moves at velocities higher than the speed of sound in the unburnt gases. The rate of flame propagation is thus far greater in a detonation than in an explosion, which is a combustion in which the velocity of flame propagation does not exceed the speed of sound in the unburnt gases. According to Wilhelm Josts Explosion and Combustion Processes in Gases, McGraw-Hill Book Company, Inc., New York (1946), pages 160 to 210, all of which are devoted to detonations, the velocity of the flame front in detonations thus far investigated is from 1 to 4 kilometers per second (about 3,280 to 13,120 feet per second) as compared to, for instance, 50 feet per second for a typical explosion.

The flame of a detonation moves into unburned gases with a velocity that is supersonic instead of subsonic, and it is initiated by and remains associated with a shock front that is characterized by almost instantaneous rise and very rapid fall of temperature and pressure. Once established in an elongated chamber, the detonation wave travels at a constant velocity (Lewis and Von Elbe, Combustion, Flames and Explosions, Academic Press,

Inc., 1951). We have found that these unique properties ice mechanically. A supersonic shock wave is thereby set: up as the high pressure gas expands into the low pressure gas. This wave travels along the tube at supersonic speed setting up associated rarefaction and compression i zones having associated high and low temperature areas,

vrespectively, in the zones sufficient to cause cracking of the make gas to acetylene. This process will be more fully set forth below with reference to drawings and examples.

It is a primary object of this invention to provide a process for utilizing shock waves to make acetylene from other hydrocarbons.

It is a further object to provide such a process wherein the shock waves are derived from either a shock tube reaction or from a detonation gun.

According to one embodiment of this invention, acety- J lene can be produced from other hydrocarbons by passing the shock wave resulting from a detonation into a confined charge of the hydrocarbon to be cracked. In order to maintain a well-defined interface between the detonation charge and the cracking charge prior to the detonation, thecharges may be physically separated by a'diaphragm or membrane which is easily ruptured by and does not objectionably interfere with the passage of the shock Wave into the cracking stock. However, it has been found that a membrane is not necessary to provide separation of the detonation charge and the cracking charge. Alternatively, an inert gas barrier may be placed I between the two charges or both charges may be flowed into the gun from opposite ends and vented at the center f thus forming a dynamic interface between the two, the

"venting preventing substantial mixing of the detonation i and cracking gas charges before the detonation. Both of these latter methods lend themselves more nearly to continuous production as it is not necessary to physically replace the membrane after each detonation. The cracking charge may be either detonable or non-detonable 7 when exposed to the shock wave from another detonation. The cracking charge may be made up entirely of the hydrocarbon to be cracked or it may be mixed with an oxidant such as oxygen. Some hydrocarbon-oxygen mixtures are not detonable unless exposed to a high energy source such as that provided by the shock wave of another detonation. Where no detonation occurs in the cracking charge, the effective penetration of the detonation shock wave into the charge seems to depend on the intensity of the detonation. Analyses indicated that a K major part of the acetylene formed in these instances was found near the boundary formed by the separating memi brane, the area of most effective penetration. Where the components of the cracking stock are in such proportions 3 to result in a mixture detonable by the stock wave-resulting from detonation of the detonation charge, impingement of the shock wave thereagainst results in a continued propagation of the detonation in the cracking stock.

These and other objects, features and advantages will become apparent from the following detailed description A membrane is placed in the tube defining two chambers therein, the ends of the tubebeing closed. Gas pressure is built up on one side of the membrane while the other side is evacuated and partially filled with a hydrocarbon make gas. When the Pr differential be w e e Woch mbe s .,.i ,.s flicient, the membrane is ruptured either by pressure or of theaccompanying drawings in which:

Fig. 1 is a schematic longitudinal sectional View of one form of reaction apparatus in which the process of the present invention may be practiced;

Fig. 2 is a view of a longitudinal section through another form of reaction apparatus capable of carrying out the principles of the present invention;

Fig. 3 is a longitudinal sectional view of a shock tube adapted for carrying out the method of the instant invention; and

Fig. 4 is a longitudinal sectional view of a modified form of detonation gun in which a membrance is not utilized to separate the detonation and make gases.

Referring more particularly to the drawings, Fig, 1

shows a reaction apparatus 10 which comprises one chamber 12 for forming and detonating a detonation charge and another chamber 14 for receiving a cracking charge. Detonation chamber 12 is in the form-ofan shorter detonation chamber. The detonating mixture is introduced through a connection 56 into the detonation chamber 50 which is provided'with a spark plug 58 near the entrance of the chamber for ignition of the charge.

elongated retort several times as long as it is wide and is The cracking chamber 52 is a short narrow chamber connected at one end with the cracking chamber through a having a diameter substantially equal to the diameter of flanged union 16 which supports a membrane 18 extendthe detonation chamber at the end which is connected to ing transversely across the opening between the two chamit. It is normally separated from the latter during the bers. The membrane may, for example, be made of cell'ocharging period by a diaphragm 60 which is rupturable by phane or thin kraft paper. A combustible gas, such as the detonation. Diaphragm 60 is supported by the union hydrogen, is supplied through pipes 20, and an oxidizing 62 connecting the cracking and detonation chambers. gas, such as air, is supplied through a pipe 22, to amixing Cracking stock is fed into the cracking chamber through chamber 24 in such proportions as to form a detonable an inlet connection 64 at a rate controlled by valve 66. gaseous charge mixture which passes through a short Chambers 50 and 52' are provided respectively with vents connecting pipe 26 into an ignition chamber 28 provided 68 and 70, Whi h are disposed on opposite sides of the with spark plug 30. The end of the cracking chamber 14 diaphragm 69. Product acetylene is removed through remote from the detonation chamber is closed bya cap Vent 70. 32 formed with an opening for receiving a fuel supply There is wide latitude of choice in the dimensions of line 34 through which the cracking stock is introduced the detonation chamber, provided a detonation can be into cracking chamber. A suitable valve 36 is disposed f m d dileeted. III the form of apparatus of g- 1, in supply line 34 to control the feed into the cracking detonations can be successfully produced with lengths chamber. Chambers 12 and 14 are respectively provided from fifteen to one hundred and twenty inches when using with vents 38 and 40 located on opposite sides of the a one-inch inside diameter chamber. Various sizes of separating membrane 13. Acetylene product is withcracking chambers ranging from a one-inch diameter drawn through vent 40. chamber one inch long to fourteen inches long have been It is to be understood that the term make or cracking successfully used. Acetylene yields achieved with crackcharge refers to the hydrocarbon to be operated on by ing chambers two inches in length were as good as those the shock Wave in either the detonation gun or the shock achieved with the longer chambers. In the apparatus of tube while the term detonation charge refers to the gas in Fig- '2, ni l e nation m r of ix nd fifteen which the detonation is initiated. inches in length were used successfully, both chambers The detonation chamber may, for example, be filled having inside diameters of 0.364 inch at one end' and with a charge comprising a stoichiometric mixture of hy- 1.05 inches at its other end. Cracking chambers were drogen and oxygen, and the cracking chamber may be similar to these mentioned above in connection with'Fig. filled with a gaseous hydrocarbon with or without added 1. The thickness of the separating membrane may also oxygen. The desired reaction is effected by igniting the be varied so long as it does not objectionably interfere detonation charge in chamber 12. The resulting shock W th the passage of the detonation. Cellophane was used wave ruptures the separating membrane, and passes into successfully and kraft paper ranging in thickness from the cracking stock. .0004 to .0016 inch was employed. Recovery decreased In the modification of Fig. 2, a shorter and conicallyas the thickness of the diaphragm increased. shaped detonation chamber 56 is employed. Use of this 40 he detonation wave may be generated in a wide shape is economical for it permits a reduction in the Variety Of fluid mixtures Capable of Producing detone' amount of fuel required to produce a detonation wave tioils- A sieiehiemetfie mixture of hydrogen and oXygeh having a diameter substantially equal to the inside diamhas been found y Suitable, it Produces a Strong eter of the cracking chamber 52, Le. the cone shape of the detonation and eohdensehle products- As for Cracking detonation chamber reduces the volume of the chamber Sioek, either a gaseous vaporized finely dispersed without reduction in the diameter of the detonation wave liquid hydrocarbon with Without added oXygeh can available f penetrating the Cracking Charge be used. Suitable hydrocarbons, which have been used It is important to present a detonation wave over the lhchlde methane, h P P e and 'p Good entire cross section of the cracking chamber in order to ylelds have been h h 111 using eXygeh'hydfoeal'boh subject a maximum amount of cracking stock to the mlxtures that are rich 111 hydrocarbondetonation Wave, f the fl ti penetration f the Table I shows the results of several runs using various detonation may not extend throughout the length of the cracking Stocks in the detelleiieh and cracking apparatus cracking chamber. A helix 54 of copper wire is placed of g- 1 0f the dreWiIlgS- In each instance, the detonatnear the ignition end of the detonation chamber 56- in ing mixture used was made up of 67% hydrogen and 33% order to accelerate the formation of detonations in the oxygen.

TABLE I Cracking Acetylene Stock Test Cracking Cracking Chamber Membrane Yield, Con- No. Stock 00. verted to 01H; (percent) l(132) Methane" 1dia.,21g.tin1ined 0.0004K1'aftpaper. 0.611 2'. 38

(25.6 cc. VOL). 2 (49) d0 1 dia. (16 cc. Vo1.) Cellophane 0. 356 2.22 3 ..do...- 1V( l0ii3., 1"1g. (11.6 cc. 0.0004 Kraft paper. 0.266 2. 29 4(l50) ..do 1" dia., 21g. (25.6 cc. de 1.83 7,12 5 1515113116-..- 1" ii e'.,'6"1 (84.5 cc. -do 1.85 2.30 sass n-pentane. r' riirijz' i (25.6 cc. 10 1.85 7.22 7 Propane- 1d iia 2"lg. (25.6 cc. .....de 1.95 7.6

VOL).

it will be seen that the, yield obtained in acracking chamber having a two-inch long diameter in run 4 was, greater than the yield obtained in acracking chamber having six-inch long diameter, as in run 5,- when employing the same cracking stock. This seems to indicate that the reaction takes place principally in the portion of the cracking chamber near the diaphragm in the area'where penetration is most effective.

-Tab1e H shows the results of several runs made with conically shaped detonation chambers, the cracking stock being ethane and the detonating mixture being 67% hydrogen and 33% oxygen in each instance. The cracking chamber used for each run was a one-inch diameter pipe two inches long, and having a volume of 25.0 cc.

. from chamber7 4 through line 85 and valve 86.

Example I METHANE BY DETONATION PRODUCED SHOCK WAVES -foot length of -inch-LD. steel tubing wasconnected in a straight line with a 10-foot length of Kw-in.

ACETYLENE FROM TABLE II;

, Acet- Percent Test No. Cracking Detonation Chamber Membrane ylene Hydro- Remarks.

Stock Yield carbon (cc.) converted 8 (170) Ethane. Filgbg tyipe, lg. cone, 0.364 to 0.0004 Kraft paper-. 1 1.73 6( 82 f ia. 9 (174) do-.- Filgbg tydpe, 6" lg. cone, 0.364 to do 1.82 5.18

' a. v v 10 (180) do... Fig. 2 type, 6"1g. cone, 0.364 to --do 2.10 8.27 2 coil added to detona v 1.05 dia. tion chamber to reduce 1 predetonation length. 11 (267) do Filgbz type, 6"lg. cone, 0.374" to 0.0016 Kraft paper.- 1.16 4.57 Do.

12 (280) do Filgbg tyipe, 6"1g. cone, 0.364" to 0.0008 Kraft paper 1.67 6. 57 Do.

It will be seen that the use of the two-inch coil to reduce predetonation length in the six-inch conical detonation chamber produced a marked increase in the recovery J of acetylene. The effect of diaphragm thickness is also illustrated in the last three runs.

Table III shows the results of several runs made with cracking stocks having added oxygen. Apparatus of the type shown in Fig. 2 was employed, the cracking cham- Q her being one inch in diameter, two inches long and 25.6 cc. in volume and the separating membrane comprising 0.0004 inch thickkraft paper. In each instance the v detonation mixture was 67% hydrogen and 33% oxygen.

4s. TABLE III Conver- Charge Pres- Test No. Cracking Stock Acetylene sion on sure in Both a Yield Carbon Chambers Basis (5) 13 (189) 52% CH4; 48% Or 1. 31 19.7 14 (181)-- 57% CH4; 43% O2 1.30 17. 84 15 (2183-- 46% 0.11.; 54% or--- 1.32 11.2 16 (221 59% CzHu; 41% 02 1.49 9.8 17 (225).- 75% 0.Ha;25% O: 1.60 8.3 v 18 (253).- 57% 0911s; 43% 0a 1.32 3.0 Atmospheric. 19 (259)-- 57% GHQ; 43% 02" 0.98 2.35 14 p.s. .g. 20 (260)..- 57% CH 43% Oz p 1. 26 6. 66 19 p.s.1.g.

It has also been found that a barrier is not necessary 0 when a detonation is used as the shock source. In a detonation zone adjacent to a reaction zone, a detonation wave. can be initiated which travels toward the reaction zone. This detonation wave is then converted to a shock wave upon entering the reaction zone containing a 65. gas mixture incapable of sustaininga detonation. Theshock wave then travels at diminishing strength through; the non-detonable medium.

Equipment to carry out this modification of the invent-ion is shown in Figure 4. The reaction vessel con- 70' sists of a detonation chamber 73 and a reaction chamber 74. A gas mixturecapable of sustaining a detonation enters chamber 73 through line 75 and valve 76 and flows out of line 77 and valve 78. A hydrocarbon reactant simultaneously enters chamber 74 through line ,79 and 755-;

ID. steel tubing by a ;-in-I.D. T whose side outlet led to a valve. The outer end of the A -in. tube was closed with a fitting bearing a valve and an ignition plug. The outer end of the -in. tube was closed with a valve. A gas mixture (67% hydrogen+33% oxygen by volume) known to develop detonation under the conditions of the experiment'was put into the 7 in. tube and a methanecontaining gas mixture (67% methane+33% oxygen) known to be incapable of supporting detonation was put into the -in. tube by admitting streams of these compositions through the valves at the ends of the 'yi -in. and. -in., tubes, respectively, and allowing them to escape through the valve at the central T. When the gas flows were steady, the inlet valves were closed atthe same time; then, in quick succession (to minimize mix-- ing), the outlet valve was closed and the ignition circuit; was completed. A clearly audible ping was heard immediately. Analysis by mass spectrometer of the gas in thesystem after the experiment indicated an acetylene con-, centration of 0.38% by volume; this corresponds to 0.44 cm. at room pressure and temperature.

Example I I ACETYLE PRODUCED SHOCK WAVES The apparatus was the same as thatused in-Example I, above, except that the tubes joined by the -in.-bore I T were each 5 feet in length and A -in. ID. A mixture of 67% hydrogen and 33% oxygen by volume was put' into the ignition end of the system and methane was put 3 into the other end, all at atmospheric pressure; in the way described for Example 1, above. Again, a ping was heard on ignition. Analysis by mass spectrometer of 1 the gas in the system aftervthe experiment indicated an acetylene concentration of 0.17% by volume; this corresponds to 0.31 cm. at room pressure andtemperature.

Examplelll NE FROM METHANE BY DETONATION- ACETYLE PRODUCED SHOCK WAVES The apparatus was the same as that used in Example H, above, exceptthat a pressure transducer was present in the fitting at the end of theapparatus opposite theg ignition end andv recording instruments were arranged to record. its output. A mixture of 67% hydrogen and 33% oxygen by volume was put into the ignition end of'the system and a mixture of 67% methane and 33% oxygen was. put into the opposite end in the way described for Example 1.. A ping Washeard on ignition and the record of the output of the present transducer showed that a shock wave had struck the transducer. Analysis by mass spectrometer of the gas in the system after the experiment indicated an acetylene concentration of 0.20% by volume.

A further method of operating the detonation gun shown in Fig. 4 is to flow an inert gas simultaneously into-the gun barrel with the make gas and detonationgas. This is done through the valve 78 and line 77. It has been found that satisfactory separation of the detonation and make gases is thus accomplished.

The apparatus used for the shock tube embodiment is shown in Figure 3. It consists of a compression chamber 91 and an expansion chamber 92 separated by a barrier 93, usually of cellophane. The gas used to generate the shock wave is introduced into the compression chamber 91 through line 94 and valve 95 until the desired contained pressure is obtained. The expansion chamber 92 is evacuated by means of a vacuum pump connected through line 96 and valve 97. Hydrocarbon gas or mixture is introduced to expansion chamber 92 through line 98 and valve 99 until the desired pressure is obtained in the expansion chamber 92. Usually the pressure in compression chamber 91 is considerably greater than that in the expansion chamber 92. The barrier 3 is broken either by means of excessive pressure in chamber 91 or by action of a plunger 100. On bursting of the diaphragm, the gas in the compression chamber starts expanding into the expansion chamber. A centered rarefaction wave travels from the diaphragm location back into the compression chamber at sonic speed toward the end of the compression chamber where it is reflected. The gas expanding through this rarefaction wave is cooled adiabatically and is accelerated to supersonic speeds. The cooled gas expanding into the expansion chamber adiabatically compresses the gas originally in this chamber, heats it and imparts to it a velocity equal to its own, When this compression wave generated in the low pressure gas is traveling at a supersonic speed relative to that gas, a shock wave is formed. As the shock wave travels through the expansion chamber, it heats up the hydrocarbon molecules. Additional high temperatures are attained at the outlet end of the expansion-zone. At this point the shock wave is reflected causing a recompression of the end gases. These gases are then cooled by the reflected .rarefaction' wave as well as by the on-rushingexpanding gases. The product gases are then removed through line 101 and valve 102.

It has been calculated that a shock wave produced by the sudden expansion of gas at 1.750 mm. mercury pressure into gas at 5 mm. mercury pressure will have a gas temperature behind the shock front of 5260" C. followed by a zone at 94 C. The temperature of the gases compressed by the reflected shock wave will be 10,380 C. These high temperatures followed by expansion cooling are quite suitable for conversion of hydrocarbons to acetylene.

The following examples describe shock tube production of acetylene.

Example I ACETYLENLE FROM METHANE IN THE SHOCK TUBE diaphragm from the methane and argon. When the diaphragrn burst due to the gas pressure, a shock wave formed in the tube which produced an audible report and an orange flash of light, The gas remaining in the shock tube contained 0.34 volume percent acetylene based on a mass spectrometer analysis.

Example ll PYROLYSIS OF BENZENE IN THE SHOCK TUBE A shock wave was produced by releasing hydrogen at 20 p.s.i.g. (1750 mm. Hg) into a 50:50 volumepercent mixture of methane and xenon by the bursting of a cellophane diaphragm separating the two chambers of a shock tube. The methane was 24.6% converted into acetylene, based on a carbon balance taken from the mass spectrometer analysis of the product.

Example IV PRODUCTION OF ACETYLENE FROM METHANE AND OXYGEN IN THE SHOCK TUBE Helium at 1750 mm. abs. pressure was released into a mixture of 75 mole-percent argon, 8.3% oxygen, and 16.7% methane by bursting a cellophane diaphragm separating the two stages of a shock tube. The initial downstream pressure was 12 mm. of mercury. The shock WalVt) which resulted initiated a reaction which was luminous for less than a millisecond. An analysis of the dry gas product, exclusive 'of helium and argon, based upon a mass spectrometer analysis, is as follows:

Volume-percent co O C 0 14.0

C H 0.4 0 1-1 0.4 C H 9.7 CH 14.2 H 54.8 (3.,H 0.6

This is a 45% conversion of the methane to acetylene, based on a carbon balance.

Example V AND Acetylene was produced from a mixture of methane, oxygen, and argon in a shock tube as follows: A static pressure of- 20 p.s.i.g. (1750 mm. of mercury) of hydrogen was built up in a 4-foot length of the shock tube behind a cellophane diaphragm. A 10-foot section of the shock tube downstream from the diaphragm was evacuated and then filled to 5.8 mm. Hg pressure with a mixture of 33.5% argon, 43.5% methane, and 23 volume-percent oxygen. When the diaphragm was punctured, a bright flash was observed at the Windowed section of the tube farthest from the diaphragm. An oscilloscopic trace of the signal from a photomultiplier cell showed that the light flash had dropped to below 30% of maximum intensity after one-half of a millisecond (0.0005 see). A sample of the product gas, analyzed by mass spectrometer, showed 14.65 moles of 9 acetylene per 100 moles of argon.

A complete analysis, based on 100 moles of argon is:

Example VI PRODUCTION OF ACETYLEN E FROM METHANE AND OXYGEN IN THE SHOCK TUBE Hydrogen at 20 p.s.i.g. was released into a mixture of 34.6% and 63.4% (by volume) methane at 2.7 mm. of mercury absolute, when a cellophane diaphragm separating them was burst. The shock wave which was produced caused an orange flash of light. A sample of the product gas contained 12% acetylene.

Example VII PRODUCTION OF ACETYLENE FROM METHANE AND CHLORINE IN THE SHOCK TUBE The first stage of the shock tube containing helium gas at 1750 mm. of Hg abs. was separated from a low pressure (1.5 mm. Hg) equimolar mixture of methane and chlorine by a cellophane diaphragm. A shock produced by breaking the diaphragm produced a bright visible flash in the windowed downstream section of the tube. A mass spectrometer analysis of the products showed that 46 mole-percent of the methane was converted into acetylene while 19.5% of the methane remained unchanged.

There has thus been disclosed a novel method for producing acetylene from other hydrocarbons by the use of shock waves. If a detonation gun is used as the source of the shock wave, the detonable gas and the make gas may be separated by a membrane, an inert gas barrier, or by a dynamic interface as when the two gases are vented at their junction. If a shock tube is used as a source of the shock wave, the pressure or shock wave generating gas and the make gas must be separated by a membrane; however, this membrane may be ruptured by either pressure diflerential or by a mechanical device as disclosed. However, regardless of the source of the shock wave in the make gas, the broad principles of the reaction are essentially the same, i.e., a compression with associated high temperature followed immediately by a rarefaction with associated low temperatures passing through the make gas at supersonic speeds. While specific apparatus capable of performing the method has been disclosed, it is to be understood that other apparatus could equally well be utilized to achieve the desired results. No limitations other than those specifically set forth in the claims are intended.

What is claimed is:

1. A process for transforming hydrocarbons to acetylene by use of shock waves initiated by a detonation comprising the steps of introducing a detonation charge into one end of an elongated reaction space to establish a detonation charge zone, introducing a detonable fluid make charge containing a hydrocarbon to be transformed into another portion of the reaction space, interposing a separating medium between said detonation charge and said fluid make charge, igniting the detonation charge, impinging the resulting detonation wave against the fluid make charge whereby the make charge is caused to detonate and transform a portion of the hydrocarbon of the fluid make charge into acetylene.

2. A process as defined in claim 1, in which said sep arating medium is a diaphragm rupturable by the deto nation wave of said detonation charge.

3. A process for forming acetylene from other hydrocarbons by use of detonations, said process comprising introducing a detonation charge into one portion of a reaction space having a configuration capable of sustaining a detonation, introducing a make charge containing a hydrocarbon other than acetylene into another portion of said reaction space interposing a separating medium between said charges, igniting the detonation charge, and impinging the resulting detonation Wave against the make charge, said detonation wave penetrating through said make charge and causing a rapid rise and fall of the temperature and pressure to form acetylene from the hydrocarbon of the make charge.

4. A process as defined in claim 3, wherein said separating medium comprises a diaphragm rupturable by the detonation wave.

5. A process as defined in claim 3, wherein said bydrocarbon is a saturated hydrocarbon.

6. A process as defined in claim 3, wherein said make charge is a mixture comprising ethane and oxygen.

7. A process as defined in claim 3, wherein said make charge is a mixture comprising methane and oxygen.

8. A process as defined in claim 3, wherein said detonation charge is a stoichiometric mixture of hydrogen and oxygen.

9. A process as defined in claim 3, wherein said make charge is a non-detonating hydrocarbon.

10. A process as defined in claim 3, wherein said make charge is made up entirely of a hydrocarbon from the group consisting of methane, ethane, pentane and propane.

11. The process defined by claim 3, wherein the sep. arating medium is achieved by passing an inert barrier gas into the reaction space at a point between the detonation charge and the make charge.

12. The process defined by claim 3, wherein the sep arating medium is the interface between the detonation charge and the make charge achieved by venting the detonation charge and the make charge at a point approximately midway between their points of introduction in the reaction space.

13. A process for producing acetylene from other hydrocarbons by the use of a shock wave comprising the steps of introducing a make gas into one end of a closed elongated reaction chamber, introducing a second gas into the other end of said reaction chamber, separating the two gases with a thin diaphragm, increasing the pressure of the second gas until a pressure differential exists across the diaphragm capable of initiating a shock wave in the make gas, rupturing the diaphragm, and removing the reaction products.

14. The process set forth in claim 13, wherein the diaphragm is ruptured by the gas pressure of the second gas.

15. The process set forth in claim 13, wherein the diaphragm is ruptured by mechanical means.

16. A process for producing acetylene from hydrocarbons comprising the steps of introducing such hydrocarbons into an elongated reaction vessel, subjecting such hydrocarbons to the action of a shock wave and its associated rapid rise and fall of temperature and pressure suflicient to penetrate through said hydrocarbons to cause cracking of said hydrocarbons and transform a portion thereof into acetylene, and removing from the reaction vessel the reaction products of which said acetylene constitutes a part.

References Cited in the file of this patent UNITED STATES PATENTS 2,475,282 Hasche July 5, 1949 2,690,960 Kistiakowsky et al. Oct. 5, 1954 2,832,666 Hertzberg et al Apr. 29, 1958 FOREIGN PATENTS 737,555 Great Britain Sept. 28, 1955 

1. A PROCESS FOR TRANSFORMING HYDROCARBONS TO ACETYLENE BY USE OF SHOCK WAVES INITIATED BY A DETONATION COMPRISING THE STEPS OF INTRODUCING A DETONATION CHARGE INTO ONE END OF AN ELONGATED REACTION SPACE TO ESTABLISH 